Springs embodying closed cell elastomeric material



3,231,256 SPRINGS EMBODYING CLOSED CELL ELASTOMERIC MATERIAL OriginalFiled May 26, 1961 R. L. OLSON Jan. 25, 1966 3 Sheets-Sheet l FIG. 3

INVENTOR' 334 8/0/0420 1. OLSON 84 2 BY i ATTzi zNeYs.

R. L. OLSON Jan. 25, 1966 SPRINGS EMBODYING CLOSED CELL ELASTOMERICMATERIAL Original Filed May 26, 1961 3 Sheets-Sheet 2 w UE 197761933!75101 JO JJJOJ INVENTOR 9/0 /1420 1.04:0

ATTORNEYS R. L. OLSON 3,231,256 SPRINGS EMBODYING CLOSED CELLELASTOMERIC MATERIAL Jan. 25, 1966 3 Sheets-Sheet 5 Original Filed May26, 1961 INVENTOR. 046D United States Patent 3,231,256 SPRINGS EMBODYINGCLOSED CELL ELASTGMERIC MATERIAL Richard L. Olson, Hickory Hills, Ill.,assignor to Dike-0- Seal, Incorporated, Chicago, 111., a corporation ofIllinois Original application May 26, 1961, Ser. No. 123,917, now PatentNo. 3,166,332, dated Jan. 19, 1965. Divided and this application Dec. 4,1964, Ser. No. 420,481

15 Claims. (Cl. 2671) The present application is a division of myapplication Serial No. 123,917, filed May 26, 1961, now Patent 3,166,332dated January 19, 1965, and through that application is acontinuation-in-part of my application Serial No. 696,271 filed November13, 1957, now abandoned.

This invention relates to improvements in multi-cell elastomer springs,and more particularly such springs in which the reaction means comprisemolded multi-closed cell elastomer mass or masses.

There have been previously unappreciated as well as unresolved problems,difficulties and limitations relating to various types of resilientlydeformable or flexible members of elastomeric grossly deformable (asdistinguished from bulk deformable) materials for use between relativelymovable and relatively rigid members as spring devices. As examples onlyand in general, it may be noted that prior art or previously knownmembers of flexible or elastomeric materials intended to be highlyflexibly deformable (as for a large amount of travel by deformation orto give a close or complete conformation to an engaged surface) havebeen quite limited or deficient since such solid material members had todeform or flex as wholes and their softness or flexible conformabilitywas limited or determined by the flexibility and softness of thematerial itself, which had to be relatively and undesirably stiff toprovide adequate strength, wear resistance, and other such properties.As another and more specific such example, it is noted that previousspring devices or the like of rubber or suitable elastomeric materialswere often desired to have very rapidly increasing spring rates (i.e.,to be initially very soft or of a low spring rate and progressively andto rapidly become stiffer or of high spring rates upon increasing loadsor deflections). However, simple or economic prior art forms of suchdevices have had relatively linear spring rates so that various complexand costly multi-step configurations and other expedients have beenemployed to achieve such rapidly increasing spring rates.

As another such example, it is noted that where it has been desired touse confinement in a rigid body and also to use a resilient compressionof gas or air to achieve rapidly increasing spring rates and for relatedsuch purposes that such devices have suffered from short life, sealingdifficulties, high cost and difficulties in holding high gas pressuresunder high loads or for long travels and, in general, from complexity.

A general object of this invention is the provision of members,preferably molded, having progressively and rapidly increasingstiffnesses or spring rates and, more particularly, according to anexponential curve which is preferably of a cube power or higher withoutcomplexity of form or parts.

A further object of this invention is to be found in the provision ofresiliently compressible members having an initial confinement (in arelatively rigid member) which compressibly increases to substantiallymatch the applied compressing forces and deflections, and moreparticularly to provide such increasing confinement in combination withrapidly, or with similarly, increasing spring rates.

Still another general object of this invention is to provide resilientlycompressible members or devices wherein their local volume reduction orsoft resilient compressibility permits an essentially local deformationor bending of a surface without requiring deformation or bending of thewhole of a part of such a member.

An additional general object to this invention is to be found in theprovision of a molded or similarly formed member which is initially andincreasingly confined and is readily deformable or may have greatertravel or motion by reason of a greater softness or lower spring ratetogether with hi h strength, long life and low cost.

Another additional general object hereof is to provide such a memberwhich is resiliently compressible and has air spring-likecharacteristics without the previously inherent disadvantages ofpreviously known types of air springs or the like.

A further and more specific general object hereof is the provision of adevice including a member which is flexibly deformable and resilientlycompressible by comprising, at least in material part, unconnected, gasfilled bubbles or closed cells of flexible material whose main portionis relatively rigidly confined and with a projecting portion to give aprogressively increasing confinement with, and to match, displacementsor applied pressures and more particularly to also give progressivelyand rapidly increasing spring rates.

Objects of the spring aspects of this invention relate to the provisionof a spring device including a member which comprises at least inmaterial part of gas filled sealed cells or bubbles of interconnectedflexible (and preferably elastomeric) walls and which has a relativelyrigidly confined portion and an integral projecting portion to becompressed into said confined portion by an always engaged compressingsurface member or always by the simultaneous engaging of all, of theouter end of this projecting portion by a compressing surface, and,

more particularly, where such a projecting portion is curved and shapedto prevent the formation of any sharp bends, corners or pockets as it isprogressively compressed and confined, preferably,

with a rapidly increasing'spring rate, from the compression of its allconfined gas volumes.

A yet further object of the invention is to providenew and improvedmulti-closed cell elastomeric spring devices having utility as returnsprings, bumpers or buffers, machinery mounts and other types ofsupporting springs, and the like.

Other objects, features and advantages of the present invention will bereadily apparent from the following detailed description of certainpreferred embodiments thereof taken in conjunction with the accompanyingdrawings, in which:

FIGURE 1 is an axial or end plan view of a spring unit includingelongated or circular, concentric, molded spring members;

FIGURE 2 is a transverse enlarged fragmentary sectional detail viewtaken substantially on the line II-II of FIGURE 1;

FIGURE 3 is a sectional view similar to FIGURE 2 but showing a modifiedform of the invention;

FIGURE 4 is a similar sectional view of a further modification;

FIGURE 5 discloses a stacked arrangement of disk through a circular orbutton type spring and assembly;

FIGURE 10 shows a spring assembly similar to FIG- URE 9 but with thespring substantially compressed;

and

FIGURE 11 is asectional perspective view of an elongated spring orbuffer device comprising an embodiment of the present invention.

In FIGURES 1 and 2 is disclosed a spring device where-in a plate or disk413 may comprise a relatively thin sheet metal stamping or the likewhose thickness is proportioned to the symmetry of the loads to beencountered. This stamping has opposite faces 417 and 417 carryingmulti-closed cell elastomer compressible spring members 420 ofelongated, concentric circular ring form mounted in respectiveoppositely opening alternating grooves or trenches 424 in the faces ofthe plate.

Eachof the compressible spring members 420 is of a compressible,cellularconstruction and preferably comprises an elastomer possessing a highdegree of resiliency. Whilecellular rubber as such may be used,different types of synthetic'resino us materials that are capable of being molded and set to a compressible, cellular elastomer may be used. Ina desirable construction, the spring material is"confor-med to thecontour of the grooves or trenches 424 andbonded thereto with suchthorough adherence that during compression the spring Will not separatefrom the surfaces defining the groove;

In a preferred method the material used for the springs 420 is such asmay be cured or set in situ by vulcanization'or baking, catalyticcuring, and the like. For example, where a synthetic plastic materialsuch as polyu'rethane,-and the like, is used, it may be molded in asuitable fluent state and cured cold. Where the composition is avulcanizable type it may include a suitable natural or synthetic rubber,a plasticizer, a vulcanizing agent; and agas liberating agent capableupon the application of heat of liberating substantial quantities of gasand thereby swelling or expanding the elastomeric composition andproducing a self-sustaining, resilient, elastic multi-cellular spongerubber-like body of any preferred resistance to compression, that isspring rate.

In effectingthe curing, by whatever method suitable or preferred, amaster plate is provided with grooves matching the grooves 424- andhaving the preferred width and depth and shape to provide a ridge ribportion 425 on each of the spring members. A suitable quantity of theraw materials for the spring members 420 is placed into the respectivegrooves of the plate 413 and the master plate or plates assembledtherewith to complete chambers with the confronting grooves. Theassembly is then held together while exothermic or catalytic curing andexpansion to provide the cellular structure proce'eds, or is placed in asuitable ourin-g oven and subjected to proper temperature ortemperatures for the proper length of time to effect expansion andcuring of the spring members into a homogeneous cellular, sponge bodyuniformly throughout the length and Width of the spring members. Byhaving the surfaces within the grooves 424 treated to assure activebonding of the material of the spring members 420 thereto as an incidentto the curing process, and by having the surfaces of the master plateopposing the plate 413 in each instance treated to assure non-adherencethereto of the material of the spring members 42%, upon separation ofthe master plate or plates from the member 4'13 after curing, the springmembers 420 separate from the master plate but are carried bonded to themember 413 within the grooves 424.

Various pressure responsiveness and spring resistance and returncharacteristics can be attained by suitable variations incross-sectional size and shape and density, as Well as composition ofthe spring members 420, location and number of the spring bodies 420,the proportion of confinement of the spring body, and so forth.

The compressible spring members 424 are com-prised either substantiallyentirely, or at least in material part, of fluid or gas-filled closed orsealed, discrete, small, unconnected, independently acting, generallybubble-like cells with common Walls of flexible elastomeric material,with at least part of the bubble-like cells being gas-filled, wherebythe spring members are resiliently deformable and bulk compressible atleast partly into the confined part or portion thereof by resilientcompression of the gas in the gas-filled bubble-like cells and moreparticularly in the confined part of the compressible member for therebyresisting movement of the relatively movable part of the spring member.toward the confined part with rapidly increasing spring rate. Althoughit is preferable to have the bubble walls of material which isinherently and materially elastomeric, in view of the presence of thenumerous gas-filled bubbles, it will be seen that the flexible cell wallmaterial need have little or no rubber-like or elastomeric properties,if it is desired to use such a material, since compressibility of thenumerous small volumes of confined gas gives the resilient bulkcompressibility and returnability characteristics useful for theadvantageous spring act-ion.

The cells or bubbles need not all be of the same sizes, materials orother properties, since advantages of this invention may be realized bythe use of various mixtures 0r blends of different types of materialsfor the same or different cells or bubbles. As an example, smaller andinherently stronger bubbles 420A may be dis-posed in regions wheregreater strength is required, such as adjacent to or in the unconfinedportions or areas of the spring members such as in the ridge portions425, with larger bubbles 420B, which have lower inherent spring ratesand initial stitfnesses, that is are more readily compressed, in thewell-protected interior or confined portions of the spring member.

Not all of the fluid or deformable material filling the bubbles or cellsneed be a gas which is elastically compressible, since a suitablepercentage or part of the bubbles in a given deformable spring member,or even in all of them, may be filled with some other material such as aliquid to provide different properties by its substantialincompressibility, or particularly, to give a high degree of friction orenergy absorption where a highly viscous material or liquid is soemployed. This permits the introduction of any reasonably desired amountor percentage of frictional action into a deformable member according tothis invention and provides for a number of very simple and desirableforms of resiliently returnable, frictional spring devices with combinedor built-in shock absorbing characteristics by reason of such viscousliquid filled cells, which are deformed during the preferably longtravel or relatively flexible deformation of such a unitary member.Where a substantial percentage of the bubbles are filled with a readilydeformable and friction producing and highly viscous liquid, theirfriction producing action will be very much greater than that given bythe relatively much smaller amount of cell wall material, particularlysince it is usually not feasible or practical to provide adequatelystrong cell walls from very soft elastomeric materials or from lowdurometer rubber-like materials having high degree of internal frictionand a high deformability or softness.

The spring stiffness or softness and the shape of the spring rate curveof any of the various forms of spring members according to thisinvention will also be modified by the cell wall thickness and by theelasticity of the elastomeric material. The percentage or part of thetotal volume of such a deformable member which is occupied by theflexible or elastomeric wall material in relation to the remaining partof the volume occupied by gas. will determine how much such a spring canbe bulk com-- pressed, neglecting the very small compressibility of the;elastomer itself.

Depending on the desired properties and results and for different typesof materials and applications as dis;

closed herein, the flexible or elastomeric, cell wall material shouldform from .a maximum of about 85% to 90% of the total volume of suchdeformable spring member where high compression engaging pressures mustbe resisted, down to percentages as low as about to 4% of the totalvolume for the cell wall material where light unit loads or low pressureapplications are to be met and/or where high strength materials such,for example, as urethane sealed cell or bubble sponges are employed.

Another important aspect of this invention resides in selection of thepreferred range of absolute sizes (or corresponding volumes) of at leastthe effective preponderance of the fluid filled bubbles, taken inconnection with, or for, a preferred bubble wall or separation thickness(determining the initial percentage of confined gas) and the stiffnessor springiness as well as the strengths of the particular material usedfor such walls in any case. There are a number of different factorsalfecting the relationships for the preferred upper and lower sizelimits for the bubbles. For high strength materials and for highpercentages of confined fluid or gas, the upper limit for the diametersof the effective preponderances of the bubbles or closed cells may be onthe order of about 0.02 to 0.03 inch to thereby benefit by the rapidlyincreasing resistance against bursting and flextural strength asafforded by the at least partial confinement of the spring masses. Thelower such limit, particularly for low percentages of con-fined gas is apractical one, depending on the ability to form interbubble walls of acorrespondingly reduced thickness with particular materials and byparticular expanding, blowing, or bubble-forming techniques, and isabout 0.001 inch diameter or somewhat less for strong material andrelatively thick walls. The smaller the bubbles are (for a givenpercentage of confined gas down to practical limits) the more effectiveor stronger they become in providing a soft deformable outer layer,particularly, and in resisting bursting out of relatively high pressuresat unconfined areas. The larger bubbles may be used, if desired, in theless critical regions or deep in the initially confined part of the bodyor even in the inner portion of the projections 42.5. In such regionsthere may also be a higher percentage of confined gas or relativelythinner walls.

Of course, for ease of forming or molding the bulk compressible springbodies, particularly Where they are of small cross-section, it will nodoubt be found simpler to make them generally the same throughout exceptat the progressive transition or boundary region, as it merges into askin which may, if preferred, be provided at the unconfined surfaces ofthe spring members. Thicker and tougher or more Wear resistant, "but ofcourse less flexible, skins may be used where needed for rough use andthe like, but where preferred no appreciable skin need be used becausethe bubble walls at the boundary layers will confine the fluid withinthe bubbles.

It is also contemplated under the scope of this invention that the fluidor gas in the bubble-like cells may be under a relatively high initialpressure (up to the strength limits of the cell wall material) in anyform of the invention.

An important feature resides in that the partial confinement of thespring members increases progressively and in a related or matchedfashion to the compressing or engaging loads as the projecting portionis compressed or displaced down into the initially confined portion.This has a number of advantages including the resulting ability of thespring members of gas-filled cells to withstand very high pressureswithout bursting of the cells or outer skin since the bubbles areincreasingly con-fined and restrained against bursting as the pressuresincrease.

It is also highly desirable (particularly for elongated membersunder anyof the forms hereof), that the entire extent or length of the outersurface or top of the crown or ridge rib should always be substantiallyengaged to thus always apply a matched and increasing confinement to theentire extents or lengths of such outer surfaces as they are compressedaccording to progressively increasing spring rates. The avoidance ofabrupt changes in compression and confinement of such spring membersalong their extents or lengths is particularly important for highmaximum pressure applications in high load springs. This preventsbursting at any one less restrained portion. Further, in more lightlyloaded spring members it prevents fatigue, undue flexure or bends atpoints where the compression (and the resultant increased confinements)differ.

Referring now to FIGURE 2, in one possible use of the spring member 413,it may be interposed between opposing respective compressing memberssuch as fiat metal plates 419 and 419' having, respectively, a surface418 opposing the spring member surface 417, and a surface 418' opposingthe spring member surface 417. These substantially rigid plates 419 and419' will make full engagement with all of the crown surfaces 427 of therespective opposing spring members 420. Further, and if preferred, theplates and spring member, or any preferred series or stack of the springmembers or spring members and plates may be suitably guided as by acenter pin or guide rod 464 (FIG. 12).

In applications of units such as 413 in spring devices or in resilientlyreturned or other types of friction or energy absorbing devices, it willbe noted that the spring members 420 may also usefully serve as sealssince they may trap a fluid, and particularly, a compressible gas in theannular spaces 430 between them to thereby increase their spring orreturn action. It is also to be understood that the elongated members420 may be arranged in other patterns than circular since the closedloops may be of any suitable shapes and, in fact, need not necessarilyform completely closed loops.

In FIGURE 3 is shown a spring unit 513 which may comprise a plate ormember of substantial thickness having multi-closed cell elastomerspring members 520 provided with bubble masses 520a and 52Gb andpartially confined within grooves or trenches or recesses 524, with theprojecting portions 525 adapted to be bulk compressed into the body ofthe respective spring member substantially as described for the springmembers 420. However, instead of the generally concave shape of the sidewalls as in FIGURE 2 comprising smaller volume or depth side wallpockets 433 formed with rounded bottom due to curve 433a, the springunits 520 are provided with sloping walls 533 from crowns 577. Theparticular generally hexagonal cross-section and shape of the springmembers 520 makes them especially suitable for lower compression springsintended for light duty or for light loads and a relatively small amountof compression of the projecting portion into the cavity.

In FIGURE 4 is disclosed a plate like unit 613 which is similar to theunit 413. However, the unit 613 has bulk compressible seal members 620which have very importantly different profile or cross-sectional shapefor their pro ectmg portion 625. The spring members 620 in each instancehas discrete, small closed bubble-like cells 620A and 620B. The life ordurability of the projecting portions 625 and the skin 629 thereon (ifpresent) where the projecting portion has a cross-section or profile sothat it has a smoothly progressive changing and reversing curvature fromone side to the other. As shown, such curvature is of the ogee typewithout any abrupt changes or sharp bends or high stress points eitherinitially or at any time during its deflection and deformation to anarrower width as it is pressed down into the cavity or trench byaprogressively widening engagement either with a rigid surface or withanother such deformable member. This ogee curve may thus smoothly andprogressively flatten into a straight line. From the curved crown 62-7there is a smoothly curved transition to the sides 633 and then to thelateral base surfaces 628 which may merge with the contiguous surface ofthe plate 613. A distinct advantage of this ogee curvature shape of thespring member projection resides in that as the projection flattens outunder compression there is no tendency to draw in at the outer edges ofthe outer extremity surface areas 628. Variousmodifications of the ogeecurvature may be afforded for different conditions, such as differentrib heights, bubble spring rates, bubble wall strengths and stiffnesses,and other properties ofthe gas-filled bubble members and theirconfinement as has been disclosed.

FIGURE may be considered as of a more or less: schematic nature anddiscloses how a stack of suitable length of spring plate units 813having bulk compressible multi-cellular elastomeric springs 820 may beprovided on a rod or mandrel between abutments 065 and 866 and wherebycompression forces 834 are adapted to be: applied. Such stacks ofsuitable length are useful toachieve a desired amount of total travel ordeflection and also to permit by their metal plates with their heatconduction, a much higher degree of heat dissipation, which is quiteuseful in cases of shock or energy absorption where the-devices aresubjected to rapidly repeated or cyclic vibrations or deflectionstending to build up heat in the spring members 820.

In FIGURES 7 and-8 a stack of disk-like plate units 913 mounted on a rodor mandrel 964 is shown in which. the circular grooves or trenches inwhich the multi-closed cell bulk compressible elastomeric spring members920 are confined are machined or cast. Such heavier and stronger plateunits are useful for very high pressures and loads. It will beunderstood that the spring members 920 may have any preferredcross-sectional profile such as that shown in FIGURES 2 and 3 andprovided with crowns 927, skins 929, if preferred, and side surfaces933. As shown at 918 andat 982 in FIGURE 7, spaces are closed betweenrespectively adjacent rings of the crown-to-crown. spring members andbetween the innermost ring of spring members and the mandrel 964. Asshown in FIGURE 8, the projecting portions of the spring members havebeen flattened into nearly straight lines as the surfaces 917 and917'ofopposing members 913 are nearly at their end stop or engagingpositions wherein the bulk compressibility of the gas-filled bubbles inthe spring members 920 will give a very high resisting pressure and theair trapped in the spaces 981 and 982 will afford additional resistanceto complete contacting of the spring carrying disks. Protection againstovercompression of the spring members is had when the opposing surfacesof the metallic disks bottom against each other.

Reference will now be had to certain devices as represented'in FIGURES9, 10 and 11 which are especially suitable to be used as spring orresilient return devices such as end bumper springs, friction devicessuch as shock absorbers or vibration isolating mountings or supports forvibrating equipment or machinery or as combined spring and frictionaldevices.

In FIGURES 9 and 10 the suitable strength casing or recess formingmember 1013 has a suitably shaped and suitable depth, circularcross-section cavity 1024 which is here illustrated as initiallyconfining the major portion of the volume of a round or button-likecompressible member which is designated as a whole by 1020 and has theexposed side edges 1028 which are here horizontal and substantiallycoplanar with, or coextensive with, surface 1017. The projection portionor crown 1025 has still another form of ogee curve profile orcross-section as shown at 1020, 1033A, 1033 and 1027 and is here asurface of revolution. The outer surface 1027 is here shown asflattened. This flattening may be done in various ways either initiallyor subsequently but is here compressibly flattened after member 1020 hasbeen suit-ably molded so that surface 1027 is suitably secured as byadhesive cement or bonding to the upper, and here flat, surface 1018 ofthe engaging plate-like member 1019, which is large enough in extent toextend out beyond the sides 1028 so that it may, if necessary, engagesurface 1017. It will of course be understood that the diameter of1019-may be made smaller so that it can never engage surfaces 1017, ifdesired. As shown, the lower face of 1019 has a suitable protectivecovering such as the bonded on rubber bumper layer 1018A. The surface of1018A may be struck or engaged, either continuously or intermittently,by any suitable means such as the plunger 1019B. Member 1019 maybesuitably guided as by having its peripheral edges inturned as shown intocylindrical portions 1019A which are guidingly engaged in thecorrespondingly cylindrically shaped guide surf-aces of guide member1089. Portions 1019A slide around the outside of 1013. It will, ofcourse, be understood that only a simple light plate may be used at1019; Also such a plate or thelike may be omitted, particularly. wherethe lower end of 1025 is to engage a suitable surface or especiallywhere all of such a surface is substantially always springily engaged innormal use.

FIGURE 9 shows another form of means .to adjust the initially confinedvolume or its initial pressure. The axially adjustable screw base 1013has a curved end 1024' and threads 1055 which are self-locking.Adju-stmentof the Whole end of 1024 will also change the shape of curve1033.

Another profile shape is shown by the profile curve 1033a shown in dotsand dashes. This illustrates that various other heights and ratiosofvolume of the projecting portionrelative to the volume of theconfinedportion may be employed under this invention and depending, as disclosedabove, on the desired springrate curve and also, of course, upon therelative volume of compressible gas to solid material in the entiremember 1020. Such a lower projection 1033a is desirable with the highervdensity or more gas or Wider spaced bubbles 10200.

As shown in FIGURE 10 the ogee surface curve of the projection portion1025 has been partially and smoothly compressed into a different butgenerally similarly ogee curve with the width or diameter of itsflattened top 1027 materially increased by its progressively increasedengagement area with surface 1018. As also illustrated in this figure,the edges of portion-s 1028 remain essentially horizontal or coplanarwith 1017.

It is to be understood that forms such as FIGURE 9 (like the other formshereof) may also employ in the matrix or body of elastomer differentsizesof bubbles including the larger interior bubbles 1020A and thesmaller and stronger bubbles 1020B adjacent the exposed surfaces of theprojecting portion and merging progressively into even smaller bubblesto form the strong but highly flexible and deformable skin 1029. Thefact that the compressible skin is, in effect, formed by progressivelysmaller bubbles is important in preventing the outward bulge at theouter edges, as at 1028, under high compression. In this connection itis to be noted that the compressibility or rubber-like properties of theskin itself are particularly important in circular forms ornon-elongated forms such as this since the skin surface has to undergo amaterial transverse compression in two dimensions, or reduction in areaas it is progressively engaged as shown. Thus the use of rubber-like orhighly elastomeric material (particularly for the projecting portion andits skin portion), is particularly useful in such forms although it isalso desirable in the elongated forms disclosed herein wherein there isbending and only a one dimensional compression or a reduction intransverse width of the engaged surface.

FIGURE 11 shows another elongated or generally striplike form whereinthe member 1120 has its initially confined and much larger volumeportion held in relatively rigid means 1113.

FIGURE 11 also shows that the inner confining surface 1124 of therelatively rigid confining or thin metal member 1113 may be extendingaround over the flat side edge portions 112% by turned in or bent overportions 1113 (which may be readily formed by extrusion or the like).This member 1113 also includes a bottom and longitudinally extendingrecess or corrugation 1113B to stiffen it and to reduce the central partof the confined volume. It will be understood that a plurality of suchstiffening bends or corrugations may be employed if desired. This figureshows the side edges 1119' of the long engaging member designated as awhole by 1119 as being curved downwardly to extend around and enclosethe corresponding sides of member 11-13. It will thus be seen that thisformation gives a higher degree of enclosure and may be used for abetter appearance. The outer and exposed surface of member 1119 may besuitably finished or may employ the rubber bumper or the rubber layer1118A suitably bonded or cemented in place.

In this embodiment, similarly as in the embodiment of FIGURE *9, theclosed cell elastomeric material body has a projection 1125, herein inthe form of a rib, afiorded with a top 11-27. Within the body mass ofthe member 1120 are larger interior unconnected cells or bubbles 1120Awhile the projection 1125 has smaller cells or bubbles 112013. On itsexposed surfaces, the projection 1125 is provided with a curved, in thisinstance generally ogee, contour 1133 merging with the margins 1128. Theexposed surfaces of the projection 11 2.5 and the marginal areas 1128are desirably provided with a highly flexible and deformable skin 1129.

This member 1119 is particularly useful when such an assembly or deviceis employed as a bumper, as for automobiles or the like. In such uses,it is important that the entire length or extent of the rib 1125 ofmember 1120 is always engaged and compressed because of long cover plate1119. This device of FIGURE 11 is also intended to be used as a lengthof a vibration isolating or vibration absorbing mount for vibratingequipment or machinery. It is to be understood that suitable lengths orshapes of such devices may carry the weight of vibrating equipment todamp out or convert this vibration into heat. Devices according to thisinvention are superior for such uses in View of the extreme softnessenabled by the high strength, gas-filled cells. This softness and thelow spring rates permits the highly desired long travel needed for suchdevices together with a high degree of strength and the ability towithstand high extreme loads or pressures. Plate 1119 may be omitted ifthere is a suitable full length engaging surface.

Referring to the curves of FIGURE 6, it is to be noted that curves I andII may be considered as typical or representative curves for highlycompressed spring members under this invention, and which consist eitherentirely or substantially of gas-filled bubbles or sealed cells. Thesetwo curves I and II are generally similar except that curve II has asharper break at its knee portion or between its relatively stiff regionand its relatively soft region, which are here somewhat arbitrarilydivided by the vertical dividing line K.

For purposes of comparison, and to bring out certain of the attributesof high pressure curves typical of the bubble forms of this invention(as shown in curves I and II, two curves S and "C show respectivelysquare and cube form curves or curves which are according to theequations Y=X and Y=X respectively. It is thus apparent that curvestypical of this invention (or such as curves I and II) have the rapidlychanging curvature of curves to a high exponent. As illustrated, suchexponent may be materially higher than the cube power. They may also bemore nearly linear.

It is, of course, to be understood that within the purview of thisinvention, the relative volume of gas in the bubbles, the relativeamount or percentage of confinement and other factors may be changed tochange the shapes of such curves or shift them horizontally orvertically. Thus, high pressure curves such as I and II, and which arehere considered as typical or illustrative only, may be made to havemuch more gradually changing slopes so that they become more like squarerate curves. In

10 fact, they may have rates of changing curvature of less than squarerate if desired.

Considering curves I and II from another aspect, it is to be noted thatthey are asymptotic not only to the X or deflection axis but to theordinant asymptote illustrated by A. This illustration brings outgraphically that as the very small unit volumes of gas in the bubblesare compressed to a very high degree so that these small volumes of gascome up to a pressure or effective rigidity approaching that of theconfining flexible and preferably elastomeric walls, the entirecompressible members become very rigid indeed and approachasymptotically the line A. That is, they progressively become infinitelystiff.

It will thus be apparent that resiliently compressible members accordingto this invention (and devices as employing them) may be arranged tonever bottom or so that the travel limiting surface will never bump orengage together with a jerk. This last is particularly useful in springdevices or friction devices where it is desired to prevent suchbottoming or bumping. This is illustrated by the vertical line L inFIGURE 6 which is beyond line A.

In contrast, however, vertical line L illustrates that such stop orrigid surfaces may engage to limit the further compression or furtherpressures and rupturing forces acting on the resiliently compressibledevices.

For such high compression seal purposes and for other applications wherevery high degrees of compression or high pressures are used, therelatively stiff region to the right of the vertical line K is employed(as well as the relatively soft region). In such case the very rapidlyincreasing spring rates (from the bubbles) are often particularlyimportant or desirable, particularly for uses such as end bumpers andother cases where it is desired that the spring stiffness increase veryrapidly indeed near the end of its travel.

In contrast, however, for other spring, for frictional deviceapplications it is sometimes only desirable or useful to employessentially the relatively soft region or to the left of vertical lineK. In such cases, the combination of extreme softness together withstrength, is particularly useful and the rapidly increasing spring rates(to the extent that a certain percentage of the bubbles are filled witha gas) is of value primarily in giving greater strength and inwithstanding excess loads or pressures.

Curve P is shown in FIGURE 6 to generally illustrate the nature of anequivalent curve for such compressible members when they are madeentirely or predominantly of open cell or porous cellular andelastomeric material. As is shown here (with the vertical ordinants andthe increasing spring rates of this curve P somewhat exaggerated forpurpose of illustration) the open or porous form has a high degree ofsoftness and an almost linearly increas ing spring rate with relativelylittle rapidly increasing slope or spring rates until the air issubstantially all pressed out of the various sizes of interconnectedvoids (which end point is not illustrated here). v As noted above, thisopen or porous form is less desirable since it does not have the highstrength with softness and requires the undesirably thicker outer skinfor practical uses.

It is also to be noted that curves I and II of FIGURE 6 also representvalues obtained from tests run by an engineering laboratory on doubleend disk units according to this invention made substantially inaccordance with the disclosure of FIGURE 7 with the trench beingapproximately /2 wide at its face, A" deep, 4" wide at its bottom andthe rib being approximately /3 high, wide at its top and A." wide at itsbase.

For curve I, a single double ended, 6' OD. disk was tested. It had oneach side, three concentric ring bubble cellular elastomer bodies asnoted above and with outer trench face diameters of approximately 5 4%and 2 /2". For similar but sharper break curve II, a similar single,double ended 4" OD. disk was tested. It had two concentric such rings oneach side with trench face outer diameters of approximately 3 /2" and of2%". As measured by liquid displacement the total volumes of the ribsfor the 6" unit and the 4" unit, for one side each, were about 2.17 and0.55 cubic inches respectively and the corresponding volumes of only thetotals of initially confined parts were about 3.97 and 1.59 cubic inchesrespectively. The 6" disk for curve I was softer and had a lower densityor higher percent of gas since its two inner rings were of about 75%elastomer and its outer ring was of about 67% elastomer (leaving about25% and 33% mostly nitrogen gas respectively). The 4" disk for curve IIwas stiffer and denser having about 87% elastomer (leaving 13% of thetotal as confined gas). It is noted that these two different area andvolume units gives curves approaching nearly the same asymptote A. It isalso to be noted that the gas cells or bubbles in this general type ofrubber-type formulation tend to merge or interconnect into each other asthey get too large or at very high percentages of total gas and thislimits the effective upper size limit for the bubbles. The upper sizelimits given of 0.02 to 0.03" are for generally single ornon-interconnected bubbles. Thus some or a few such multiple bubbles maybe actually larger without undue detriment in performance. In bothtests, the bubble bodies carried over 120,000 pounds pressure withoutfailure and with no material permanent set.

In all forms hereof the shape, height and volume (relative to theconfined volume and relation to the remaining volume left for thecompressed gas in the bubbles so the projection is compressed into therecess) of the projection will materially affect the shapes of typicalcurves such as I and II of FIGURE 6. It may also be noted that if thespring members are made of solid rubber or the like, the initial part ofa curve such as curve I will be much steeper or stiffer even though therubber is as soft as can be practically used, The shape of theprojection may give a square or even cube type of curve for a relativelylimited range of pressures or deflections after which the unconfinedportions of such a solid rubber member will fail by bursting out orextruding out. The fatigue life under cyclic use will also be quite lowfor solid rubber. All of this is in contrast to the advantages andfeatures of this invention and particularly for its fluid or gas-filledbubbles and its absence of any material permanent set or failures forvery high deflections and loads. For these and related reasons, solidelastomeric bodies are not used in any of the several forms orapplications hereof.

Referring to all of the several illustrated forms of this invention, itis to be noted that the resiliently compressible members need not bebonded or cemented in place but may be mechanically held in position.However, it is usually desirable to have such members cemented orotherwise bonded in place when they have confined portions as disclosedherein. The confining member or structure need only be relatively morerigid and thus may be of plastic or other somewhat yieldable material inall forms hereof. It is also to be noted that the air spring-likecharacteristics given by gas-filled cells or bubbles under thisinvention and as illustrated by curves I and II in FIGURE 6, haveproperties and features which are highly desirable and advantageous overpreviously used flexible or rubber-like air bags or the like where oneor more relatively large volumes of air are confined since theseflexible bags fail by bending flexure and require relatively thick andstrong walls. Also such bag devices are rela: tively costly and complexcompared to the long lived and simple arrangements possible under thisinvention. The above described, much higher bursting strengths of thesmall bubbles of this invention are quite important here and cooperateto give desirable new results, especially for high unit pressures inspring devices and for friction devices.

What I claim is:

1. In combination: a first, relatively rigid part having a recess, abutton-like flexibly deformable and resiliently bulk compressible springbody of small closed, discrete gas-filled, bubbles with common walls offlexible material, said recess confining a substantial portion of theinitial volume of said body against flow, said spring body having atleast one integral projection extending outwardly from said recess, therelative initial volumes of said confining recess, of said total gasvolume of said bubbles and of said projection permitting substantiallythe entire volume of said projection to be compressively deformed anddisplaced into the initial volume of said confined portion bycompression of the gas in said bubbles and said projection having anouter end to be engaged and moved by a second part to bulk compress saidprojection into said confined portion thereby to resist movement of saidsecond part toward said rigid part.

2. A spring device as defined in claim 1 wherein the gas pressures ofthe cells or bubbles and their spring rates progressively and rapidlyincrease with compression and with correspondingly increasingconfinement of the spring mass or body as the confinement of the entirevolume of the projecting portion or projection is asymptoticallyapproached, and including a second relatively movable part tocompressively engage the outer end of the projecting portion orprojection and having a normally never bottoming, relatively rigid stopsurface not engaging said confining means or recessed rigid part untilafter substantially complete confinement of the projecting portion orprojection at a relatively high pressure.

3. A spring device adapted for resisting movement of opposed memberstoward one another comprising, a supporting member having a plurality ofrecesses therein and a surface from which the recesses open, respectivebulk compressible spring masses having substantial respective portionsthereof mounted in partially confined relation within the respectiverecesses and having respective portions projecting beyond said surfaceand generally tapered away from the sides of the recess toward thecrowns of the projecting portions, said masses having in at least theconfined portions thereof a substantial proportion of small discretegas-filled bubble-like cells whereby a member opposing said supportingmember and engaging the outer ends of the projecting portions of saidmasses will be resisted in movement with increasing spring rate as theprojecting portions of the masses are bulk compressed toward theconfined portions of the masses.

4. A spring device as defined in claim 3, wherein said recesses are inthe form of concentric grooves and the bulk compressible masses areclosed rings, said recesses and the confined portions tapering inwardlyfrom the outer sides of the recesses.

5. A spring device for resisting movement of opposed members toward oneanother comprising a plate having opposite faces provided with recesses,and bulk cornpressible elastomeric spring masses seated in partiallyconfined relation within the recesses and having bulk compressibleprojections extending beyond the faces of the plate and generallytapered away from the sides of the recesses toward the crowns of theprojections, said projections being engageable at their crowns withopposing members to resist approach of such members toward the plate bybulk compression of the spring members into the confined portionsthereof with increasing spring rate.

6. A spring device as defined in claim 5, in which said recesses on theopposite faces of the plate are relatively staggered, with the recesseson one side of the plate lying along side the recesses on the oppositeside of the plate and having common walls therewith.

7. A spring device comprising a plurality of disks, means mounting thedisks in concentric stacked relation, and bulk-compressible elastornericspring masses between said disks, said disks having recesses in whichthe respective spring masses are seated to a substantial depth withportions of the spring masses projecting from. the recesses toward theopposing disks and tapering to. a new rower width than the width of therespective recesses and so proportioned in their extent from therecesses with respect to the widths of the recesses as to avoid turningover or bulging onto the sides defining the respective recesses whenplaced under compression toward said recesses, so as to be compressibleinto the confined portions of the spring masses upon movement of thedisks toward one another without pinching between the recess sides andthe compressing disk, confinement of the spring masses in said recessesretaining the masses against flow under the compression and thereby asthe projecting portions of the spring masses are compressed toward andinto the confined portions of the spring masses re sistance to movementof the disks toward one another increase-s according to an asymptoticcurve.

8. A spring device comprising an elongated substantially rigidsupporting member providing a channel of substantial depth, anelastomeric bulk compressible spring mass body having a substantialportion thereof mounted in said channel and confined thereby againsttransverse flow and having a rib like projection extending substantiallybeyond the channel and affording a crown against which an opposingmember is adapted to be engaged, said projection being contouredrelative to said substantial portion so that said projection iscompressible toward and into said body, said body having therein asubstantial proportion of small closed discrete gas-filled bubble-likecells affording bulk compressibility to the body, and said supportingmember having a rigid rib-like projection extending into saidsubstantial portion of the body in substantially symmetrical relationopposite said rib for reducing the volume of the substantial bodyportion opposite the rib-like projection of the body and especiallyadapting the device for use as a bumper, machinery mount and the like.

9. A spring device comprising opposed members which move toward oneanother, each of said members having a surface area opposing the surfacearea of the other memher, said surface areas being movable toward oneanother When the members move toward one another, at least one of saidsurface areas having a recess opposing the other of said areas, a bulkcompressible resiliently flexible spring mass of a closed cellelastomeric material at least a substantial portion of the volume ofwhich comprises small, generally bubble-like gas cells which arecompressible at relatively high spring rates, said spring mass having asubstantial portion thereof filling said recess and the mass beingthereby confined against flowing under compression to the extent that itfills said recess, another portion of said mass projecting from saidsubstantial portion and out of said recess toward said other surfacearea and tapering to a narrower width than the Width of said recess andso proportioned in its extent from said recessed surface area relativeto its width as to avoid turning over toward the sides defining saidrecess when placed under compression toward said recess, and saidprojecting portion being bulk compressible toward and into the body ofthe mass responsive to engagement of the projecting portion by saidother surface area on relative movement of the members toward oneanother and as the compression progresses affording increasingresistance to said movement according to an asymptotic curve due to saidconfinement of said substantial portion in said recess.

10. A spring device as defined in claim 9, in which said projectingportion has in the uncompressed normal condition thereof a generallyflattened crown and arcuate side shape.

11. A spring device as defined in claim 9, in which said projectingportion is in its uncompressed normal condition of an all-over multiplecgee profile.

12. A spring device as defined in claim 9, wherein the surface of theprojecting portion is in the normal and uncompressed condition thereofof a smoothly reversely curved profile joining substantially fiat areasof said portion in said recess adjacent to the edges of the recess so asto avoid abrupt changes in curvature during deformation of saidprojecting portion under compression.

13. A spring device as defined in claim 9, including means carried bysaid member having said one surface area operative on that portion ofthe mass within the recess to adjust the initial volume of therecess-filling portion of the mass.

14. A spring device comprising in combination: a relatively rigid firstpart affording a confinement area, a flexibly deformable and resilientlybulk compressible spring member having a substantial part of its volumeof filled, small, closed, discrete generally bubble-like cells withcommon walls of flexible elastomeric material at least part of saidbubble-like cells being gas filled, a major part of the volume of saidcompressible spring member being operatively secured within and confinedagainst flow in said confinement area, said spring member having atleast one initially substantially unconfined outwardly projectingportion, and a second and relatively movable part spaced from said firstpart and having a surface to which said projecting portion ispermanently secured and by which said projecting portion is adapted tobe resiliently deformed and bulk compressed at least partly into saidconfined portion by resilient compression of the gas in said gas-filledbubble-like cells in the confined portion for thereby resisting movementof said second part toward said first part with rapidly increasingspring rate.

15. A spring device comprising in combination: a relatively rigid firstpart affording a confinement area, a flexibly deformable and resilientlybulk compressible spring member having a substantial part of its volumeof filled, small, closed, discrete, generally bubble-like cells withcommon walls of flexible elastomeric material, at least part of saidbubble-like cells being gas filled, a substantial portion of the volumeof said compressible spring member being within and confined againstflow in said confinement area, said spring member having at least oneinitially substantially unconfined, outwardly projecting portion,adapted to cooperate with a relatively movable part spaced from saidfirst part and having a surface to engage said projecting portion toresiliently deform and bulk compress it at least partly into saidconfined portion by resilient compression of the gas in said gasfilledbubble-like cells in the confined portion and thereby resist movement ofsaid relatively movable part toward the first part with rapidlyincreasing spring rate, said spring member including therein closedcells which are filled with a viscous liquid material to provide a highfriction upon deformation of the spring member as a result ofcompression of said projecting portion into said confined portion.

References Cited by the Examiner UNITED STATES PATENTS 1,470,048 10/1923Barker 152313 2,685,269 8/1954 Manson 2671 2,686,667 8/1954 Willison etal 267--1 2,716,787 9/1955 Harris 296-4411 X 2,744,847 5/ 1956 Orr.2,995,057 8/1961 Nenzell 277171 3,011,218 12/1961 Mitten 20-69 3,045,7047/ 1962 Williams.

FOREIGN PATENTS 907,856 3/ 1954 Germany.

3,535 1883 Great Britain. 530,630 12/1940 Great Britain. 555,694 9/1943Great Britain.

ARTHUR L. LA POINT, Primary Examiner,

W. B. WILBER, Assistant Examiner.

1. IN COMBINATION: A FIRST, RELATIVELY RIGID PART HAVING A RECESS, ABUTTON-LIKE FLEXIBLY DEFORMABLE AND RESILIENTLY BULK COMPRESSIBLE SPRINGBODY OF SMALL CLOSED, DISCRETE GAS-FILLED, BUBBLES WITH COMMON WALLS OFFLEXIBLE MATERIAL, SAID RECESS CONFINING A SUBSTANTIAL PORTION OF THEINITIAL VOLUME OF SAID BODY AGAINST FLOW, SAID SPRING BODY HAVING ATLEAST ONE INTEGRAL PROJECTION EXTENDING OUTWARDLY FROM SAID RECESS, THERELATIVE INITIAL VOLUMES OF SAID CONFINING RECESS, OF SAID TOTAL GASVOLUME OF SAID BUBBLES AND OF SAID PROJECTION PERMITTING SUBSTANTIALLYTHE ENTIRE VOLUME OF SAID PROJECTION TO BE COMPRESSIVELY DEFORMED ANDDISPLACED INTO THE INITIAL VOLUME OF SAID CONFINED PORTION BYCOMPRESSION OF THE GAS IN SAID BUBBLES AND SAID PROJECTION HAVING ANOUTER END TO BE ENGAGED AND MOVED BY A SECOND PART TO BULK COMPRESS SAIDPROJECTION INTO SAID CONFINED PORTION THEREBY TO RESIST MOVEMENT OF SAIDSECOND PART TOWARD SAID RIGID PART.